An artificial heart lung apparatus is used during conventional cardiac surgery. The artificial heart lung apparatus is mainly configured from a blood reservoir, a blood pump, a heat exchanger, a blood circuit, an oxygenator, and the like. In this type of artificial heart lung apparatus, firstly blood (venous blood) that was removed from veins of the patient and blood (cardiotomy blood) that is withdrawn from the field of operation are sent to a blood reservoir, and temporarily stored in the blood reservoir. Furthermore, blood is sent to the heat exchanger by the blood pump, and the heat exchanger adjusts the blood temperature. In the oxygenator, gas exchange (carbon dioxide removal and oxygen addition) is performed on the temperature-adjusted blood. Finally, the blood is returned to the body of the patient as arterial blood.
This type of artificial heart lung apparatus provides a temporary substitution for the function of the heart and lungs during cardiac surgery. In the artificial heart lung apparatus, before returning the blood to the patient, foreign material or bubbles that have become mixed in the blood during surgery must be removed. For example, JP-H5-317420 (called “Patent Document 1” hereinafter) discloses a blood reservoir (blood reservoir including a cardiotomy reservoir) that removes simultaneously bubbles and foreign matter such as bone fragments, soft-tissue fragments, or the like from blood.